The invention generally relates to hot oil fryers for the continuous hot oil frying of large quantities of food products as in large scale food process lines. More particularly, the invention relates to such a hot oil fryer which is combined with thermal oil heating and heat exchange housed within or attached to the same cabinet as for the bath for the frying oil.
This application is commonly-invented in part with U.S. Pat. No. 6,305,274, entitled “FRYER FOR FOOD PROCESS LINES,” which document is incorporated herein in its entirety.
Nowadays, some hot oil fryers for large-scale food process lines have oil baths for the frying oil that might measure about thirty feet (˜9 m) in length and sixty inches (˜1½ m) wide. Whereas the foregoing represents a relatively large model of such continuous fryers for large-scale food process lines, the matter of ‘scale’ in the matters of large-scale food process processing is a separate matter.
FIG. 1 is a schematic showing selected equipment for a very-large scale food processing factory. This factory is running (for example and without limitation) at least three large-scale food process lines. Each one of the three lines requires its own dedicated large-scale hot oil fryer. The first fryer has—for the sole purpose only of heating the frying oil in the frying oil bath—a rated power draw of one million BTU/hr (˜1,000,000 kJ/hr, or kilo-joules per hour). The middle fryer has a corresponding rated power draw for the same purpose of a half million BTU/hr (˜500,000 kJ/hr). The furthest fryer has a rated power draw for heating the frying oil only of eight hundred thousand BTU/hr (˜8000,000 kJ/hr)(wherein a BTU and a kJ are approximately equal in value).
FIG. 1 is furthermore typical of the prior art for not only (merely) large scale but also ‘very’ large scale food processing operations. That is, the frying oil in the fryers in indirectly brought up to heat by an intermediate medium, namely, thermal oil.
Frying oil these days is predominately any of a number of vegetable-based cooking oils, most which can be found in home kitchen (whereas fat or lard and the like have long fallen out of disfavor). Thermal oil is more akin to engine oil. It is not suitable for human consumption.
FIG. 1 shows that a combustion-fired thermal oil heater is the original source of the power output for the heating the frying oils of all three fryers. The combustion-fired thermal oil heater combusts either a gas like propane (eg, a liquified petroleum gas, or LPG) and compressed natural gas (eg., CNG) or else a fuel oil like kerosene and so on. In other words, typical combustion-fired thermal oil heaters runs on a suitable gas or fuel-oil fuel. The options everyday are growing, with the greatest increase in options nowadays being led by biofuels and the like.
Suitable combustion-fired thermal oil heaters are available from and without limitation GTS Energy of Norman, Okla. and Marietta, Ga. Power outputs of suitable combustion-fired thermal oil heaters range anywhere from between and without limitation four hundred thousand BTU/hr (˜400,000 kJ/hr) and seventy-five million BTU/hr (˜75,000,000 kJ/hr).
In FIG. 1, the preferred combustion-fired thermal oil heater has a rated output of three and one-half million BTU/hr (˜3,500,000 kJ/hr). In other words, the preferred combustion-fired thermal oil heater has a little excess capacity for the maximum power draw of all three fryers running at full blast at the same time, or, three million three hundred thousand BTU/hr (˜3,300,000 kJ/hr).
Indeed, the excess capacity is probably needed for heating losses along the system. As FIG. 1 shows, it is popular to site the combustion-fired thermal oil heater outside of the factory, and plumb the conduits carrying the heated thermal oil to each of the three fryers. It is typical that any or all of the fryers can be as far as two hundred feet (˜60 m) distant.
Inefficiencies arise when the factory of FIG. 1 has changed its business operations such that it will never again ever run the first and the further fryers (ie. , the two fryers with the higher power draws). Whatever food product was being produced by those lines is being discontinued, and is presumptively never going to be re-introduced.
The factory of FIG. 1 is left in the following predicament. It has a combustion-fired thermal oil heater with a power output (three and a half million BTU/hr or 3,500,00 kJ/hr) rated at seven times the power draw of the sole half million BTU/hr (˜500,000 kJ/hr) fryer left running.
The largest corporations may not care. But niche food companies specializing in healthy alternatives will likely be only frying less food product in the future even if their food-product output grows. This already seen in potato chips and corn chips wherein the offering are any of fried, kettle-cooked, baked and so on.
It is likely that a lot of food product will always be fried in the future. It is also believed that many food company's really do not want excess capacity with combustion-fired thermal oil heating, in the belief that, the demand for that excess will not be returning.
What is needed is improvements which overcome the shortcomings of the prior art in the matters of combustion-fired thermal oil heating for indirect heating of the frying oil for hot oil fryers used in continuous hot oil frying of large quantities of food products as in large scale food process lines.
A number of additional features and objects will be apparent in connection with the following discussion of preferred embodiments and examples.